Add support for KerasNLP library (#616)

Following recent work to integrate KerasNLP library with the Hub, let's
add it in our libraries list. KerasNLP is based on Keras3 but for now
let's focus on the KerasNLP side of things (we also have on-going work
for Keras but that's orthogonal).

This PR will add a pretty name for "KerasNLP" tag + add urls to official
docs and github repo.
We will be able to generate code snippet in the future as well but [it
should be
clarified](keras-team/keras-hub#1529 (comment))
first. I suggest that we merge this PR "as-is" and add support for code
snippets later when it's ready.

About download counts, KerasNLP uses a `config.json` file so it should
already count correctly.

Bonus: first KerasNLP models on the Hub?
https://huggingface.co/google/gemma-2b-it-keras/discussions/2. Model can
be loaded with:
```py
import keras_nlp

gemma_lm = keras_nlp.models.GemmaCausalLM.from_preset("hf://google/gemma-2b-it-keras")
```
:tada:

Co-authored-by: Eliott C <[email protected]>

Author: Wauplin

packages/tasks/src/model-libraries.ts

@@ -185,6 +185,12 @@ export const MODEL_LIBRARIES_UI_ELEMENTS = {
 		filter: true,
 		countDownloads: { term: { path: "saved_model.pb" } },
 	},
+	"keras-nlp": {
+		prettyLabel: "KerasNLP",
+		repoName: "KerasNLP",
+		repoUrl: "https://keras.io/keras_nlp/",
+		docsUrl: "https://github.com/keras-team/keras-nlp",
+	},
 	k2: {
 		prettyLabel: "K2",
 		repoName: "k2",